The question was not an invitation to make a dogmatic statement by citing one of the many, many holy books created by the human species in an attempt to explain certain physical and philosophical quandaries (the creation of the universe/earth/life, the problem of evil, etc. etc). Some of these things have already been explained by science; some of them haven't but eventually will, and perhaps some never will. But do not issue or imply dogmatic statements like, "aliens are not in the Bible, therefore they cannot exist." It is this kind of ridiculous, fallacious thinking that has resulted in all the problems the huWwman species faced and continues to face.
Science has proven beyond a reasonable doubt that the conditions for life can occur all over the universe and that the universe is made up of similar elements that can be found all across it. It is not a stretch to postulate that other highly intelligent lifeforms do indeed exist elsewhere in this universe. Thinking that they will ever visit us, or trying to determine their thought processes, intentions, or even their experience of reality, is where science (nor the Bible) cannot help . . . at the moment.